I sat my courses the "traditional" way by having the SS course, a period of approx 3 weeks then the SD course. What did this give me? It meant that I went into my exams with an extra 3 weeks SS revision. I think it also gave me a better understanding of the links between SS and SD. At more of an emotive level, I felt far more confident and relaxed because I did my studying at a far more relaxed pace.
I don't think you can underestimate the difficulty of the exam. A pass rate of approx 54% suggests that it is difficult, and any advantage you can give yourself that gives you that marginal point, could be the difference between a pass and a fail.

Intrigued to know why you have chosen (or have been forced) to sit the course this way. Will you be attending the revision day? How long will it be between the course and the exam? Personally I just sense that you being asked to do this to support someone elses agenda, and not to maximise your chance of passing and / or gaining some useful knowledge that makes you better at your job.

I think having the three months between the course and the exam changes thing!
I also took my exams 3 months after my course, but I was very lucky in that my employer gave me the space to do as much revision as necessary.
In my opinion, whatever you may lose in having the two courses back to back, you gain in having an extended study period. Of course doing this raises a different questions - Can you keep your motivation? Will you get the time to revise? Will other things get in the way? As long as you can resolve these, I personally don't see a problem in doing this.